<?php
/** 
 * The specialized expression provider for MySQL
 * 
 * PHP version 5.3
 * 
 * @category  ODataProducer
 * @package   ODataProducer_UriProcessor_QueryProcessor_ExpressionParser
 * @author    Anu T Chandy <odataphpproducer_alias@microsoft.com>
 * @copyright 2011 Microsoft Corp. (http://www.microsoft.com)
 * @license   New BSD license, (http://www.opensource.org/licenses/bsd-license.php)
 * @version   SVN: 1.0
 * @link      http://odataphpproducer.codeplex.com
 * 
 */
use ODataProducer\UriProcessor\QueryProcessor\ExpressionParser\Expressions\ExpressionType;
use ODataProducer\Providers\Metadata\Type\IType;
use ODataProducer\Common\NotImplementedException;
use ODataProducer\Common\ODataConstants;
use ODataProducer\Providers\Metadata\ResourcePropertyKind;
use ODataProducer\Providers\Metadata\ResourceType;
use ODataProducer\UriProcessor\QueryProcessor\ExpressionParser\IExpressionProvider as IExpressionProvider; 
/**
 * IExpressionProvider implementation for SQLServer NorthWind DB
 *
 * @category  ODataProducer
 * @package   ODataProducer_UriProcessor_QueryProcessor_ExpressionParser
 * @author    Anu T Chandy <odataphpproducer_alias@microsoft.com>
 * @copyright 2011 Microsoft Corp. (http://www.microsoft.com)
 * @license   New BSD license, (http://www.opensource.org/licenses/bsd-license.php)
 * @version   Release: 1.0
 * @link      http://odataphpproducer.codeplex.com
 */
class NorthWindDSExpressionProvider implements IExpressionProvider
{
    const ADD                  = '+';
    const CLOSE_BRACKET        = ')';
    const COMMA                = ',';
    const DIVIDE               = '/';
    const SUBTRACT             = '-';
    const EQUAL                = '=';
    const GREATERTHAN          = '>';
    const GREATERTHAN_OR_EQUAL = '>=';
    const LESSTHAN             = '<';
    const LESSTHAN_OR_EQUAL    = '<=';
    const LOGICAL_AND          = 'AND';
    const LOGICAL_NOT          = 'not';
    const LOGICAL_OR           = 'OR';
    const MEMBERACCESS         = '';
    const MODULO               = '%';
    const MULTIPLY             = '*';
    const NEGATE               = '-';
    const NOTEQUAL             = '!=';
    const OPEN_BRAKET          = '(';
    // The default parameter for ROUND sql function-call
    private $_default_round = 0;

    /**
     * The name of iterator
     * 
     * @var string
     */
    private $_iterName;

    /**
     * The type of the resource pointed by the resource path segement
     *
     * @var ResourceType
     */
    private $_resourceType;

    /**
     * Constructs new instance of SQLSrverExpressionProvider for NorthWind DB
     * 
     * @param string $iterName The name of the iterator
     */
    public function __construct()
    {
    }

    /**
     * Get the name of the iterator
     * 
     * @return string
     */
    public function getIteratorName()
    {
      return null;
    }

    /**
     * call-back for setting the resource type.
     *
     * @param ResourceType $resourceType The resource type on which the filter
     *                                   is going to be applied.
     */
    public function setResourceType(ResourceType $resourceType)
    {
    	$this->_resourceType = $resourceType;
    }

    /**
     * Call-back for logical expression
     * 
     * @param ExpressionType $expressionType The type of logical expression.
     * @param string         $left           The left expression.
     * @param string         $right          The left expression.
     * 
     * @return string
     */
    public function onLogicalExpression($expressionType, $left, $right)
    {
        switch($expressionType) {
        case ExpressionType::AND_LOGICAL:
            return $this->_prepareBinaryExpression(self::LOGICAL_AND, $left, $right);
            break;
        case ExpressionType::OR_LOGICAL:
            return $this->_prepareBinaryExpression(self::LOGICAL_OR, $left, $right);
            break;
        default:
            throw new \InvalidArgumentException('onLogicalExpression');
        }
    }

    /**
     * Call-back for arithmetic expression
     * 
     * @param ExpressionType $expressionType The type of arithmetic expression.
     * @param string         $left           The left expression.
     * @param string         $right          The left expression.
     * 
     * @return string
     */
    public function onArithmeticExpression($expressionType, $left, $right)
    {
        switch($expressionType) {
        case ExpressionType::MULTIPLY:
            return $this->_prepareBinaryExpression(self::MULTIPLY, $left, $right);
            break;
        case ExpressionType::DIVIDE:
            return $this->_prepareBinaryExpression(self::DIVIDE, $left, $right);
            break;
        case ExpressionType::MODULO:
            return $this->_prepareBinaryExpression(self::MODULO, $left, $right);
            break;
        case ExpressionType::ADD:
            return $this->_prepareBinaryExpression(self::ADD, $left, $right);
            break;
        case ExpressionType::SUBTRACT:
            return $this->_prepareBinaryExpression(self::SUBTRACT, $left, $right);
            break;
        default:
            throw new \InvalidArgumentException('onArithmeticExpression');
        }
    }

    /**
     * Call-back for relational expression
     * 
     * @param ExpressionType $expressionType The type of relation expression
     * @param string         $left           The left expression
     * @param string         $right          The left expression
     * 
     * @return string
     */
    public function onRelationalExpression($expressionType, $left, $right)
    {
        switch($expressionType) {
        case ExpressionType::GREATERTHAN:
            return $this->_prepareBinaryExpression(self::GREATERTHAN, $left, $right);
            break;
        case ExpressionType::GREATERTHAN_OR_EQUAL:
            return $this->_prepareBinaryExpression(
                self::GREATERTHAN_OR_EQUAL, $left, $right
            );
            break;
        case ExpressionType::LESSTHAN:
            return $this->_prepareBinaryExpression(self::LESSTHAN, $left, $right);
            break;
        case ExpressionType::LESSTHAN_OR_EQUAL:
            return $this->_prepareBinaryExpression(
                self::LESSTHAN_OR_EQUAL, $left, $right
            );
            break;
        case ExpressionType::EQUAL:
            return $this->_prepareBinaryExpression(self::EQUAL, $left, $right);
            break;
        case ExpressionType::NOTEQUAL:
            return $this->_prepareBinaryExpression(self::NOTEQUAL, $left, $right);
            break;
        default:
            throw new \InvalidArgumentException('onArithmeticExpression');
        }
    }

    /**
     * Call-back for unary expression
     * 
     * @param ExpressionType $expressionType The type of unary expression
     * @param string         $child          The child expression
     * 
     * @return string
     */
    public function onUnaryExpression($expressionType, $child)
    {
        switch($expressionType) {
        case ExpressionType::NEGATE:
            return $this->_prepareUnaryExpression(self::NEGATE, $child);
            break;
        case ExpressionType::NOT_LOGICAL:
            return $this->_prepareUnaryExpression(self::LOGICAL_NOT, $child);
            break;
        default:
            throw new \InvalidArgumentException('onUnaryExpression');
        }
    }

    /**
     * Call-back for constant expression
     * 
     * @param IType  $type  The type of constant
     * @param objetc $value The value of the constant
     * 
     * @return string
     */
    public function onConstantExpression(IType $type, $value)
    {    	
        if (is_bool($value)) {
            return var_export($value, true);
        } else if (is_null($value)) {
            return var_export(null, true);
        }

        return $value;
    }

    /**
     * Call-back for property access expression
     * 
     * @param PropertyAccessExpression $expression The property access expression
     * 
     * @return string
     */
    public function onPropertyAccessExpression($expression)
    {
        $parent = $expression;
        $variable = null;
        $isFirstLevelPrimitive = is_null($parent->getParent());
        if (!$isFirstLevelPrimitive) {
        	// This propery access sub-expression in the $filter need access
        	// to level 2 or greater property of a complex or resource reference
        	// property.
        	// e.g. Customers?$filter=Address/City eq 'Kottayam'
        	//          Level_2 property access [Complex]
        	//      Customers?$filter=Address/AltAddress/City eq 'Seattle'
        	//          Level_3 property access [Complex]
        	//      Orders?$filter=Customer/CustomerID eq 'ALFKI'
        	//          Level_2 property access [Resource Reference]
        	$parent2 = null;
        	do {
        		$parent2 = $parent;
        		$parent = $parent->getParent();
        	} while ($parent != null);
        	
        	$resourceProperty = $parent2->getResourceProperty();
        	if ($resourceProperty->isKindOf(ResourcePropertyKind::RESOURCE_REFERENCE)) {
        		// Orders?$filter=Customer/CustomerID eq 'ALFKI'
        		throw new NotImplementedException(
        				'This implementation not supports Resource reference in the filter',
        				500,
        				NULL
        		);
        	} else {
        		// Customers?$filter=Address/AltAddress/City eq 'Seattle'
        		// Customers?$filter=Address/City eq 'Seattle'
        		$propertyName = $parent2->getResourceProperty()->getName();
        		if ("Address" == $propertyName) {
        			$child = $parent2->getChild();
        			$propertyName = $child->getResourceProperty()->getName();
        			if ("AltAddress" != $propertyName) {
        				return $propertyName;
        			}
        			
        			throw new NotImplementedException(
        					'This implementation not supports Customer::Address::AltAddress in the filter',
        					500,
        					NULL
        			);
        		}
        	}

        } else {
        	// This is a first level property access
        	$resourceProperty = $parent->getResourceProperty();
        	if ($resourceProperty->isKindOf(ResourcePropertyKind::COMPLEX_TYPE)
        	    || $resourceProperty->isKindOf(ResourcePropertyKind::RESOURCE_REFERENCE)) {
        		// Customers?$filter=Address eq null
        		// Orders?$filter=Customer ne null
        		// First level property access to a complex or resource reference
        		// which is not supported by $this [this implementation of IDSQP2]
        		throw new NotImplementedException(
                    'First level complex and Resource reference are not supported in the filter', 
        		    500, 
        		    NULL
                );
        	} else {
        		// First level property access to primitive property
        		return $parent->getResourceProperty()->getName();
        	}
        }
    }
    /**
     * Call-back for function call expression
     * 
     * @param FunctionDescription $functionDescription Description of the function.
     * @param array<string>       $params              Paameters to the function.
     * 
     * @return string
     */
    public function onFunctionCallExpression($functionDescription, $params)
    {
        switch($functionDescription->functionName) {
        case ODataConstants::STRFUN_COMPARE:
            return "STRCMP($params[0]; $params[1])";
            break;
        case ODataConstants::STRFUN_ENDSWITH:
          return "(($params[1]) = RIGHT(($params[0]), LEN($params[1])))";
            break;
        case ODataConstants::STRFUN_INDEXOF:
          // In SQLServer the index of string starts from 1, but in OData
          // the string start with index 0, so the below subtraction of 1
          return "(CHARINDEX($params[1], $params[0]) - 1)";
            break;
        case ODataConstants::STRFUN_REPLACE:
          return "REPLACE($params[0], $params[1], $params[2])";
            break;
        case ODataConstants::STRFUN_STARTSWITH:
          return "(($params[1]) = LEFT(($params[0]), LEN($params[1])))";
            break;
        case ODataConstants::STRFUN_TOLOWER:
          return "LOWER($params[0])";
            break;
        case ODataConstants::STRFUN_TOUPPER:
          return "UPPER($params[0])";
            break;
        case ODataConstants::STRFUN_TRIM:
          // OData supports trim function
          // We don't have the same function SQL Server, so use SQL functions LTRIM and RTRIM together
          // to achieve TRIM functionality.
          return "RTRIM(LTRIM($params[0]))";
            break;
        case ODataConstants::STRFUN_SUBSTRING:
          if (count($params) == 3) {
            // 3 Param version of OData substring
              return "SUBSTRING($params[0], $params[1] + 1, $params[2])";
          } else {
            // 2 Params version of OData substring
            // We don't have the same function for SQL Server, we have only:
            //
            // SUBSTRING ( value_expression , start_expression , length_expression )
            // http://msdn.microsoft.com/en-us/library/ms187748.aspx
            //
            // If the sum of start_expression and length_expression is greater than the number of characters 
            // in value_expression, the whole value expression beginning at start_expression is returned
            // In OData substring function the index start from 0, in SQL Server its from 1
            return "SUBSTRING($params[0], $params[1] + 1, LEN($params[0]))";        	    
          }
            break;
        case ODataConstants::STRFUN_SUBSTRINGOF:
          return "(CHARINDEX($params[0], $params[1]) != 0)";
            break;
        case ODataConstants::STRFUN_CONCAT:
            return "$params[0] + $params[1]";
            break;
        case ODataConstants::STRFUN_LENGTH:
            return "LEN($params[0])";
            break;
        case ODataConstants::GUIDFUN_EQUAL:
            return "($params[0] = $params[1])";
            break;
        case ODataConstants::DATETIME_COMPARE:
            return "DATETIMECMP($params[0]; $params[1])";
            break;
        case ODataConstants::DATETIME_YEAR:
            return "YEAR($params[0])";
            break;
        case ODataConstants::DATETIME_MONTH:
            return "MONTH($params[0])";
            break;
        case ODataConstants::DATETIME_DAY:
            return "DAY($params[0])";
            break;
        case ODataConstants::DATETIME_HOUR:
            return "DATENAME(HOUR, $params[0])";
            break;
        case ODataConstants::DATETIME_MINUTE:
            return "DATENAME(MINUTE, $params[0])";
            break;
        case ODataConstants::DATETIME_SECOND:
            return "DATENAME(SECOND, $params[0])";
            break;                
        case ODataConstants::MATHFUN_ROUND:
            return "ROUND($params[0], $this->_default_round)";
            break;
        case ODataConstants::MATHFUN_CEILING:
            return "CEILING($params[0])";
            break;
        case ODataConstants::MATHFUN_FLOOR:
            return "FLOOR($params[0])";
            break;
        case ODataConstants::BINFUL_EQUAL:
            return "($params[0] = $params[1])";
            break;
         case 'is_null':
            return "is_null($params[0])";
            break;

        default:
            throw new \InvalidArgumentException('onFunctionCallExpression');
        }
    }

    /**
     * To format binary expression
     * 
     * @param string $operator The binary operator.
     * @param string $left     The left operand.
     * @param string $right    The right operand.
     * 
     * @return string
     */
    private function _prepareBinaryExpression($operator, $left, $right)
    {
      if (!substr_compare($left, "STRCMP", 0, 6)) {
            $str = explode(';', $left, 2);
            $str[0] = str_replace('STRCMP', '', $str[0]);
            if ($right == 'false' and $right != '0') {
              if (!substr_compare($operator, '!', 0, 1)) {
                  $operator = str_replace('!', '', $operator);
              } else if ($operator == '>=') {
                  $operator = '<';
              } else if ($operator == '<=') {
                  $operator = '>';
              } else {
                    $operator = "!".$operator;
              }
              return self::OPEN_BRAKET 
                    . $str[0] . ' ' . $operator 
                    . ' ' . $str[1] . self::CLOSE_BRACKET;
            } else {
                return self::OPEN_BRAKET 
                    . $str[0] . ' ' . $operator 
                    . ' ' . $str[1] . self::CLOSE_BRACKET;
            }
        }
        
        //DATETIMECMP
        if (!substr_compare($left, "DATETIMECMP", 0, 11)) {
          $str = explode(';', $left, 2);
          $str[0] = str_replace('DATETIMECMP', '', $str[0]);
          if ($right == 'false' and $right != '0') {
            if (!substr_compare($operator, '!', 0, 1)) {
              $operator = str_replace('!', '', $operator);
            } else if ($operator == '>=') {
              $operator = '<';
            } else if ($operator == '<=') {
              $operator = '>';
            } else {
              $operator = "!".$operator;
            }
            return self::OPEN_BRAKET
            . $str[0] . ' ' . $operator
            . ' ' . $str[1] . self::CLOSE_BRACKET;
          } else {
            return self::OPEN_BRAKET
            . $str[0] . ' ' . $operator
            . ' ' . $str[1] . self::CLOSE_BRACKET;
          }
        }

        return 
            self::OPEN_BRAKET 
            . $left . ' ' . $operator 
            . ' ' . $right . self::CLOSE_BRACKET;
    }

    /**
     * To format unary expression
     * 
     * @param string $operator The unary operator.
     * @param string $child    The operand.
     * 
     * @return string
     */
    private function _prepareUnaryExpression($operator, $child)
    {
        return $operator . self::OPEN_BRAKET . $child . self::CLOSE_BRACKET;
    }
}
?>